1. Field of the Invention
The present invention relates to a disk drive flexure used in a disk drive for an information processing apparatus, such as a personal computer.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The hard disk drive comprises a magnetic disk that rotates around a spindle, a carriage that turns around a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.
A disk drive suspension is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-282624 (Patent Document 1) or U.S. Pat. No. 6,714,385 (Patent Document 2). The disk drive suspension comprises a load beam, a flexure lapped on the load beam, etc. A slider is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for access, such as data read or write. The suspension, flexure, etc., constitute a head gimbal assembly.
The flexure may be of any of various practical types corresponding to required specifications, and a flexure with conductors is one known example thereof. The flexure with conductors comprises a metal base, an insulating layer formed on the metal base, and a plurality of conductors formed on the insulating layer. The metal base is formed of a thin stainless-steel plate. The insulating layer is formed of an electrically insulating material, such as polyimide. The conductors are formed of copper. Respective single ends of the conductors are electrically connected to elements (e.g., magnetoresistive (MR) elements) of the slider. The other ends of the conductors are electrically connected to an electronic circuit, such as an amplifier.
In the flexure disclosed in Patent Document 1, a plurality of openings are formed in the metal base at predetermined intervals along the conductors. These openings serve to reduce an eddy-current loss of conductive circuit portion. Thus, the flexure, compared with a flexure without openings, can transfer data at higher speed. However, the flexure of Patent Document 1 has a problem that its crosstalk characteristics are degraded by a magnetic field that is formed around the conductors as current flows through each conductor. Crosstalk causes degradation of MR elements of a head portion or the like as well as production of noise. With the increase of the recording density of modern disks, in particular, the head portion tends to become fragile when exposed to crosstalk. Thus, crosstalk should be minimized.
The earlier the rise time of pulses used in data transfer, the more their harmonic components are, so that data can be transferred at higher speed. The higher the frequencies in the bandwidth, however, the higher the eddy-current loss is. In order to realize a high-frequency band, therefore, large openings should be formed such that the eddy-current loss of the conductive circuit portion can be reduced. On the other hand, openings should not be formed in order to improve the crosstalk characteristics. These problems can be solved to a certain degree by combining openings and insular portions, as in the case of Patent Document 2.
The load beam of the suspension disclosed in Patent Document 2 is provided with a plurality of openings that are formed at predetermined intervals along the conductors. The insular portions independent of the load beam are formed individually within the openings. The suspension with these insular portions has desirable electrical properties to overcome crosstalk. In addition, the capacitance of this suspension is higher than that of a suspension without insular portions. Thus, the suspension of Patent Document 2 has an advantage that the impedance of the conductive circuit portion and the energy consumption of the amplifier are low.
Since the insular portions of Patent Document 2 are not grounded, however, they may be charged with static electricity. As the static electricity is discharged, therefore, it may destroy the MR elements of the head portion or adversely affect signals that are transmitted through the conductors. Further, the insular portions are easily separable from the insulating layer, and the separated insular portions may move in a disk drive and contaminate it. Furthermore, high accuracy is required in locating a large number of insular portions independent of the load beam in predetermined positions relative to the individual openings, so that the yield is poor.